The Chancellor's decision to rule out sharing currency with an independent Scotland will prove to be a "monumental error", First Minister Alex Salmond is to declare.

The SNP leader will focus on George Osborne's "dive bomb" and set out his own vision for links across the UK in a lecture hosted by the New Statesman in London tonight.

Mr Osborne rejected the key Scottish Government proposal last month, just days after Prime Minister David Cameron made an appeal for Scots to vote to stay in the UK in the referendum on September 18.

The First Minister is expected to say: "In the last three weeks people in Scotland have seen an array of approaches from the UK Government - what they apparently call their Dambusters strategy. We were love-bombed from a distance by David Cameron, then dive-bombed at close range by George Osborne.

"I believe George Osborne's speech on sterling three weeks ago, his sermon on the pound, will come to be seen as a monumental error.

"It encapsulates the diktats from on high which are not the strength of the Westminster elite, but rather their fundamental weakness.

"In contrast, we will seek to engage with the people of England on the case for progressive reform."

The Chancellor repeatedly referred to an independent Scotland being "foreign" to the rest of the UK, Mr Salmond said.

"Scotland will not be a foreign country after independence, any more than Ireland, Northern Ireland, England or Wales could ever be foreign countries to Scotland," he will say tonight.

"We share ties of family and friendship, trade and commerce, history and culture, which have never depended on a parliament here at Westminster, and will endure and flourish long after independence.

"But the current dambusters rhetoric has betrayed an attitude as antiquated as it is unacceptable. From the myopic perspective of the Westminster elite, Scotland is last among equals. And every time we hear one of these interventions, telling us there are things we can't do, it elicits a clear response in Scotland: yes we can.

"On referendum day, all of the people of Scotland, for the first time, will be truly sovereign. Everyone will have an equal say in making the decision.

"And there will be a moment for everyone in Scotland, on referendum day, when they stand in the polling booth knowing they are helping to shape their country's future.

"This moment of opportunity, this moment of engaged sovereignty; this moment will come on September 18. Let's call it Scotland's hour, because on that moment, and from then on, Scotland's future will be in Scotland's hands."

A Better Together spokesman said: "This speech is a spectacular own goal from the First Minister. Not content with telling every expert or employer they are wrong, Alex Salmond now wants to pretend that a poll showing support for separation falling because of his failure to tell us what will replace the pound never happened.

"With poll after poll showing that people living elsewhere in the UK don't support a currency union, the SNP must face up to reality. Rather than engage in his usual name calling and personal attacks, it's time for Alex Salmond to tell the people of Scotland what his Plan B on currency is. Would we rush to adopt the euro or would we set up an unproven separate currency?

"People in Scotland know that a vote to leave the UK is a vote to lose the strength and security of the pound, with the negative impact that would have on the cost of mortgages, credit card bills and car loans."